GI 1: Upper GI tract Flashcards
Outline type of muscle found throughout the oesophagus?
cervical oesophagus = skeletal
upper and middle thoracic = skeletal/smooth
lower thoracic = smooth
Important structures in oesophagus that control how food when swallowed gets to the stomach?
upper and lower oesophageal sphincters
Where does the oesophagus start and end?
Starts C5 ends T10
What contributes to the lower oesophageal sphincter?
left and right crux of diaphragm, intact phreno-oesophageal ligament, angle of His and 3-4 cm of distal oesophagus is within abdomen - this all contributes anatomically to the LOS
What are the phases of swallowing?
oral phase, pharyngeal phase, upper oesophageal phase and lower oesophageal phase
Briefly outline the process of swallowing.
- chewing + saliva to prepare bolus, both oesophageal sphincters constricted
- bolus propelled to oesophagus, UOS opens reflexly, LOS opens by vasovagal reflex
- UOS closes, circular and longitudinal muscle contracts
- LOS closes as food passes through
How do the circular muscle work to allow food down the oesophagus during the upper oesophageal phase?
superior circular muscle rings contract and inferior rings dilate
What determines oesophageal motility?
pressure measurements
What is the approx. resting pressure of LOS?
~20mmHg
What happens to the pressure of the LOS during receptive relaxation?
decreases to <5 mmHg - mediated by inhibitory noncholinergic, noradrenergic (NCNA) neurons of myenteric plexus
Dysphagia =
difficulty in swallowing - localisation is important e.g. proximal or distal
Possible types of dysphagia?
- solids or fluids
- intermittent or progressive
- precise or vague in appreciation
Odynophagia =
pain on swallowing
Regurgitation =
return of oesophageal contents from above an obstruction (functional or mechanical)
Reflux =
passive return of gastroduodenal contents to mouth
What are the 2 main causes of functional disorders of oesophagus?
- abnormal oesophageal contraction
2. failure of protective mechanisms for reflux
What can abnormal oesophageal contraction cause?
hypermotility, hypomotility, disordered coordination
What can failure of protective mechanisms for reflux cause?
GORD
Hypermotility of the lower oesophageal sphincter is most commonly seen in?
Achalasia
What is achalasia?
When the LOS fails to open during swallowing leading to a backup of food within the oesophagus
How does achalasia lead to the LOS not opening?
loss of ganglion cells in Aurebach’s myenteric plexus in LOS wall leads to decreased activity of inhibitory NCNA neurones
What are the causes of achalasia?
primary aetiology unkown
secondary causes include diseases causing motor abnormalities similar to primary achalasia e.g. Chaga’s disease, protozoa infection, oesophagitis
How does achalasia progress eventually lead to the stop of peristalsis?
without inhibition the resting pressure of the LOS is higher than normal. This means the receptive relaxation phase sets in late and is too weak as the pressure in the LOS is higher than the stomach. Swallowed food stays in the oesophagus so pressure starts increasing throughout and the oesophagus starts to dilate. Eventually peristaltic waves stop propagating.
What type of onset does achalasia have?
insidious onset - symptoms can last for years without getting help
What happens without treatment?
progressive oesophageal dilatation of oesophagus
how much does achalasia increase risk of oesophageal cancer by?
28 fold
How can achalasia be treated?
pneumatic dilatation, Heller’s myotomy, Dor fundoplication, POEM (peroral endoscopic myotomy)
What is a common cause of hypomotility within the oesophagus?
Scleroderma
What is scleroderma?
autoimmune disease in which immune system attacks connective tissue under skin and around internal organs and blood vessels
What cause the hypomotility in early stages of scleroderma in the oesophagus?
neuronal defects lead to atrophy of smooth muscle of the oesophagus until peristalsis in distal portion ceases altogether
What happens to the resting pressure of LOS in hypomotility with scleroderma?
decreased resting pressure of LOS means the sphincter cannot close normally - can lead to development of GORD
- often associated w/ CREST syndrome
What is corkscrew oesophagus?
An oesophageal disorder in which there are incoordinate contractions of the oesophageal muscles. - it is a rare variant of achalasia
What features does corkscrew oesophagus present with?
dysphagia and chest pain due to incoordinate contractions, marked hypertrophy of circular muscle, corkscrew oesophagus on Barium.
How to treat scleroderma/hypomotility of oesophagus?
exclude organic obstruction, improve force of peristalsis with prokinetics however peristaltic failure is usually irreversible
How to treat corkscrew oesophagus?
may respond to forceful PD of cardia, results not as predictable as achalasia
What are some vascular anomalies that can cause dysphagia?
dysphagia lusoria (aberrant right subclavian artery), double aortic arch
What are the 3 areas of anatomical constriction in the oesophagus which could potentially be sites of perforation?
1) cricopharyngeal constriction
2) aortic and bronchial constriction
3) diaphragmatic and ‘sphincter’ constriction
What is the most common cause of oesophageal perforation?
iatrogenic - usually at OGD (oesophago-gastro-duodenoscopy)
What is a spontaneous cause of oesophageal perforation?
Boerhaave’s
What is Boerhaave’s?
sudden increase in intra-oesophageal pressure w/negative intra thoracic pressure e.g. vomiting against a closed glottis
